Frog sciatic nerves have been exposed to continuous wave (CW) and pulse microwave radiation. Rate of fatigue or loss of vitality (the ability of the nerve to continue firing under rapid stimulation) was increased in the ncerve exposed to 2.45 GHz at a specific absorption rate of 10 mW/g. In order to determine if sine-wave modulated microwaves had an increasing effect on ionic transport as reported in the literature to occur in chick brain, frog sciatic nerves were exposed to 2.45-GHz microwaves sine-wave modulated at 8, 16, and 32 Hz. It was found that a 50 mW/g specific absorption rate was required to obtain a loss in vitality with this form of radiation. This result suggests that the nerve vitality is nonlinear with respect to microwave intensity. This type of nonlinear behavior would be expected if the neural membrane is acting as a diode-like detector of the microwave field. In order to study this membrane interaction and to obtain a basic understanding of the ionic transport and gating mechanisms in excitable membranes, the giant axons of the lobster ganglia are now being studied.